Antiviral activity of polysubstituted benzimidazoles such as 5,6-dichloro-1-(.beta.-D-ribofuranosyl) benzimidazole (DRB) and some closely related derivatives has been previously described. Their activity against specific viruses, such as RNA rhinovirus and DNA herpes simplex virus type 1 and type 2, has also been reported.
Benzimidazole nucleosides are particularly attractive as potential antiviral agents because of their stability toward some major pathways of bioactive purine (bicyclic) nucleoside inactivation, e.g., deamination by adenosine deaminase and glycosidic bond cleavage by purine nucleoside phosphorylases. Benzimidazole nucleosides such as DRB have, however, demonstrated only marginal levels of activity or generally unacceptable levels of cytotoxicity, or both, thereby greatly diminishing their usefulness in the treatment of viral infections. It would thus be desirable to provide polysubstituted benzimidazoles and compositions thereof having good antiviral properties, preferably with a low degree of cytotoxicity.